Hybrid DC breakers consisting of high-speed mechanical switches and large-power semiconductor devices, with advantages of large discharge current capacity, high turn-off speed, high current limitation and the like, have become a research hotspot in the DC breaking field. To limit and break a short-circuit current with a high rate of rise, a hybrid DC breaker must be rapid in response and reliable in action so as to turn off the fault circuit at an early stage of a short-circuit fault. Generally, the power semiconductor device acts very quickly, so the response speed of the mechanical switch becomes a bottleneck that restricts the breaking performance of a DC hybrid breaker. Meanwhile, there will be a transient over-voltage greater than the system voltage at two ends of the mechanical switch when a hybrid DC breaker cuts off a short-circuit current, so higher requirements have been proposed to the design of the transfer current circuits of hybrid DC breakers. By adjusting the topology of the transfer current circuit to control the rate of the over-voltage rise at the two ends in the case of short-circuit, the clearance between the contacts of the mechanical switch is allowed to withstand a voltage generated excessively during the breaking process, so that reliable breaking is ensured.